Sandy Dumont is paid by companies to improve how their staff look. The idea is that after a session with the Virginia-based corporate image consultant, they will look nicer and so be better at their jobs.

Clients have included companies as diverse as ITT, American Express Financial Services, Rolex and Honeywell.

"I do a lot of financial institutions, business schools, anything that's very competitive," she says. Americans "recognise that this is another tool for getting ahead. They are willing to pay and do whatever they need to get on the fast track."

A work-related makeover means looking at things like clothes and shoes, make-up, glasses, hair and teeth. Some companies pay for the sessions, especially group ones, but some individuals buy their own one-on-one consultations.

In the UK and Europe, business people are a little more coy than Americans when it comes to having their appearance tweaked, says Louise Mowbray, London-based image and personal branding consultant. Nonetheless, they are starting to see the importance of image in a career.

"I get a lot of senior people, and for men there is often the sudden realisation that something could be holding them back - and that something could be that they have been wearing the same suit for 10 years."

Staff undergo a work-related makeover for a range of reasons: a promotion that means going out to press the flesh far more often, a job interview or returning to work after time out.

Richard Trevaskis, UK-based sales and marketing director of German industrial piping business Georg Fischer, decided to seek an image consultation with CMB Image.

"I do a lot of presenting and go to a lot of meetings. Before, I had just put anything on without really thinking, but dressing properly makes you feel right for the part and far more confident.

"Ninety per cent of my clients never visit our plants. I'm all they ever see - so for them I am the corporate image."

When the already smartly dressed matrimonial lawyer Ayesha Vardag sought advice from Mowbray, the session allowed her to think about the impression she wanted to convey and incorporate more of her own style into what she wore while retaining a businesslike appearance, says Ms Vardag.

Sarah Godwin, co-founder of legal recruitment firm Law Absolute, says an improvement in appearance, even in the supposedly dapper legal profession, is required surprisingly often.

"We often make minor suggestions to candidates like toning down eye shadow, taking out nose studs or second earrings, brushing or cutting hair."

Godwin recalls one candidate needing hygiene advice - she smelt: "I guess she took it because she got the job."

As well as individual consultations for senior staff, CMB Image's business development manager Audrey Hanna says group sessions can be useful.

"Although they are often done as fun team-bonding exercises, they can be an effective way of dealing with problem people who might be offended if you suggest a one-to-one."

Dumont believes it has become harder for workers to dress appropriately because of the way sartorial guidelines have shifted.

"The dotcom revolution was a terrible thing for dress. It made people feel OK about being sloppy and lazy. I call casual Friday 'casualty Friday'. It is an exercise in futility and people look awful."

Mowbray says recent blurring of smart and casual has got those with less than a firm grip on fashion into trouble. While casual in advertising might mean jeans and trainers, it is less likely in investment banking.

There may be situations though when lawyers or bankers want to appear less formal - for instance, when dealing with clients in entertainment. There are few firm rules today - except perhaps that shorts are only appropriate for landscape gardeners.

Dumont says executives who struggle with choosing clothes or who don't have enough time can seek expert advice. Appearance is important and should be part of the overall preparation for meeting clients.

"When you don't dress appropriately you raise questions about yourself," Mowbray says. "It takes 20-plus experiences to change an incorrect first impression. You don't want to put obstacles in front of yourself before you begin."